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Biomedical subjects

P Yu

Publications and source records attributed to P Yu.

At least 181 records · Page 10Linked to original sources
PubMed1994

Negative feedback regulation of IgE synthesis by murine CD23.

Immunoglobulin E is found in nanogram amounts in normal human and mouse serum. It is increased during parasitic infestations and mediates allergy. CD23, the low-affinity receptor for IgE (Fc epsilon RII), has been proposed as an important regulator of IgE synthesis. The type-II transmembrane lectin CD23 is expressed in the mouse on B cells and follicular dendritic cells. In humans there are two forms of CD23 which differ in their intracellular amino-terminal 6/7 amino acids; expression of the A-form corresponds to that of murine CD23, whereas the B-form is also found on T and other haematopoietic cells. CD23 has been implicated in cellular adhesion, antigen presentation, as a growth and differentiation factor for human B, T and plasma cells, and as a signal transduction molecule (reviewed in refs 3, 8). Here we disrupt the gene coding for murine CD23 (ref. 9) to clarify the role of CD23 in vivo and find that B- and T-cell development is normal in these CD23-deficient mice. Immune responses to the helminth Nippostrongylus brasiliensis are unaffected. In contrast, immunization with thymus-dependent antigens leads to increased and sustained specific IgE antibody titres compared with controls. Formation of germinal centres is normal. These results suggest that murine CD23 acts as a negative feedback component of IgE regulation.

Animals↗
PubMed1994

Cholecystokinin-coupled intracellular signaling in human gallbladder muscle.

BACKGROUND/AIMS: It has been shown that cholecystokinin (CCK) contracts the gallbladder muscle by utilizing intracellular calcium, but the intracellular pathways have not been elucidated. The present study was designed to characterize the signal transduction pathways that mediate CCK-induced contraction of human gallbladder muscle. METHODS: Single muscle cells were isolated from human gallbladders by enzymatic digestion with collagenase. Permeable cells were obtained by incubation with saponin. Protein kinase C (PKC) activity was determined by measuring the phosphorylation of a specific substrate peptide from myelin basic protein, Ac-MBP(4-14). RESULTS: The inositol-1,4,5-trisphosphate (IP3) antagonist heparin blocked the contractions induced by CCK. The PKC inhibitor H-7 blocked the contractions caused by low, but not high, concentrations of CCK and IP3. In contrast, the calmodulin inhibitor CGS9343B blocked the contractions induced by high, but not low, doses of CCK and IP3. Furthermore, exogenously activated calmodulin blocked the PKC-mediated contraction induced by diacylglycerol. Direct measurements of PKC activity showed that low, but not high, CCK concentrations caused PKC translocation. CONCLUSIONS: CCK contracts the gallbladder muscle via IP3-mediated calcium release. CCK activates the PKC pathway at low concentrations, whereas it activates the calmodulin pathway at high concentrations, which in turn inhibits the activation of PKC.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Effect of source and amount of supplemental fat on lactation and digestion in cows.

Thirty Holstein cows averaging 50 DIM were assigned to five dietary treatments for 75 d to determine the effects of source and amount of supplemental fat on milk yield, milk composition, and nutrient digestibilities. Diets were 1) control, 2) diet 1 plus 12% whole cotton-seed, 3) diet 2 plus 2.2% safflower oil, 4) diet 2 plus 2.2% prilled tallow fatty acids, and 5) diet 2 plus 4.4% prilled tallow fatty acids. Milk yield was increased an average of 2.1 kg/d by addition of 2.2% prilled tallow fatty acids or safflower oil to the diet (7% fatty acids) containing 12% whole cottonseed. However, when fatty acids were increased to 9.1% with additional prilled tallow fatty acids, milk yield, DMI, and fatty acid digestibility decreased. Whole cottonseed alone and in combination with all fat additions decreased milk protein concentrations. Safflower oil increased C18:0, C18:1, and C18:2 fatty acids in milk. Digestibilities of OM, NDF, and ADF were not affected by diet. Supplementation of a saturated or unsaturated fat source to increase fatty acid content to 7.0% of dietary DM increased milk yield, but a further increase in fat to 9.1% with the saturated source appeared excessive for cows yielding 30 to 35 kg/d of milk.

Animals↗
PubMed1993

Crosstalk between epidermal growth factor receptor and P-glycoprotein in actinomycin D-resistant Chinese hamster lung cells.

Multidrug-resistant cells can manifest an increase in epidermal growth factor (EGF) receptor number along with increased P-glycoprotein (Pgp) synthesis. An interrelationship of the two membrane proteins in actinomycin D-resistant Chinese hamster lung cells (DC-3F/AD X) in terms of the effect of EGF on Pgp phosphorylation was investigated. EGF was not a mitogen for the resistant cells, nor was it mitogenic for DC-3F, the parental drug-sensitive line. Brief treatment of DC-3F/AD X cells with EGF resulted in a 30-50% decrease in the level of Pgp phosphorylation, and treatment of the cells with okadaic acid, a specific inhibitor of protein phosphatases-1 and -2A (PP1 and 2A), increased Pgp phosphorylation. Okadaic acid also increased phosphorylation of Pgp in plasma membranes isolated from DC-3F/AD X cells by 30-40%. Protein phosphatase activity in extracts of cells grown in EGF-containing medium was greater by 30% than that of cells grown in standard medium, and okadaic acid inhibited the increases. The results suggested that EGF activated PP1 and PP2A in DC-3F/AD X cells and that Pgp was a substrate for the phosphatases. The properties of Pgp may be modulated by the signalling system transduced by ligand-activated EGF receptor.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Interaction between signal transduction pathways contributing to gallbladder tonic contraction.

Muscle strips were used to study the mechanisms that generate cat gallbladder tone. Strontium substitution for calcium and the protein kinase C (PKC) inhibitor H-7 abolished the tone, whereas the calmodulin antagonist W-7 had no effect, suggesting that tone depends on intracellular calcium release and the PKC pathway. Basal levels of diacylglycerol (DAG) and inositol-1,4,5-trisphosphate (IP3) were higher in gallbladder muscle than in esophageal muscle, which does not maintain tone. These data suggest that IP3 might interact with DAG to activate PKC during tonic contraction. This interaction was demonstrated in single cells in which a low dose of IP3 potentiated DAG and the potentiation was blocked by H-7. Furthermore, low doses of IP3 induced contraction, which was blocked by H-7 and unaffected by the calmodulin antagonist CGS-9343B; high doses of IP3 were unaffected by H-7 but were blocked by CGS-9343B; DAG-induced contraction was blocked by activated calmodulin. We conclude that 1) the synergistic action of DAG and IP3-calcium release, which further activates PKC, might be responsible for gallbladder tone and 2) activated calmodulin appears to inhibit the effect of PKC.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1993

[Relationship between amitriptyline metabolism and polymorphic debrisoquine hydroxylation in native Chinese volunteers].

The demethylation and hydroxylation of amitriptyline were calculated from the ratios between the area under concentration--time curve (AUC) of amitriptyline and its three metabolites in eight healthy Chinese volunteers after a single oral dose of 100 mg amitriptyline. Great interindividual differences in AUCs of amitriptyline and its metabolites were observed. HPLC method was used to determine the debrisoquine hydroxylation phenotype in seven out of the eight volunteers. Six subjects were found to be rapid and one slow debrisoquine hydroxylators. The ratio between debrisoquine and 4-hydroxydebrisoquine in urine correlated significantly with the rate of amitriptyline hydroxylation and the AUCs of amitriptyline and 10-hydroxyamitriptyline, but not with that of amitriptyline demethylation. There also was a weak correlation between total plasma clearance and the hydroxylation of debrisoquine. These data suggest that the hydroxylation of amitriptyline and debrisoquine may be regulated by similar enzymatic processes and the demethylation and hydroxylation processes in amitriptyline metabolism appear to undergo two separate pathways.

Adult↗
PubMed1992

Nucleotide binding by the poliovirus RNA polymerase.

Cross-linking of ribonucleoside triphosphates (NTPs) to specific binding sites on the poliovirus RNA-dependent RNA polymerase has been performed by ultraviolet irradiation and by reduction of oxidized nucleotide-protein complexes. The latter method approached a cross-linking efficiency of 1 NTP/molecule of enzyme. Nucleotide competition experiments suggested that the same binding site is occupied by all NTPs. Analysis of peptides produced by proteinase Glu-C and trypsin digestion and labeled with [32P]GTP indicated that a lysine residue between Met-189 and Lys-228 in the polymerase was cross-linked to NTP. Nucleotide binding was exploited for rapid purification of the enzyme by GTP-agarose affinity chromatography. In addition, a set of cloned, modified polymerase molecules with reduced or absent polymerization activity was analyzed for binding efficiency to a GTP-agarose column. Some mutations eliminated GTP binding, whereas others generated proteins with varying affinities for GTP. Incubation of the poliovirus polymerase with high concentrations of NTP, particularly GTP, resulted in a dramatic protection against heat denaturation and activity loss. These data suggest that nucleotide binding results in an alteration of the enzyme conformation or the stabilization of an ordered conformation.

Autoradiography↗
PubMed1992

Nervous control of distension-induced relaxation of the porcine lower oesophageal sphincter.

The mechanisms involved in the relaxation of the lower oesophageal sphincter induced by distension of the oesophagus and different parts of the stomach, were studied in an anaesthetized porcine model. A computer technique was developed allowing on-line digitizing of lower oesophageal sphincter (sleeve device) and intragastric pressures. Basal sphincter tone was slightly reduced by truncal vagotomy, an effect which seemed to be reversed by sectioning of the vagosympathetic trunks in the neck. Balloon distension of the body of the oesophagus, relaxed the sphincter irrespective of the denervation procedures carried out. Distension of the whole stomach with increasing amounts of air induced a dose-dependent relaxatory lower oesophageal sphincter response, which was also closely associated with the subsequent increases in intragastric pressure. Denervation procedures did not alter this dose-response relationship. The importance of intramural mechanisms was illustrated by the abolition of distension-induced effects in most animals studied after transection of the gastro-oesophageal junction distal to the sphincter. Balloon distension of the antrum elicited a smaller but significant sphincter relaxation, but the mechanisms behind this response seemed to be more complex than after insufflation of air.

Animals↗
PubMed1992

[Pasting acupoints with Chinese herbs applying in infant acute bronchitis and effect on humoral immune substances].

This report described the clinical observation of pasting acupuncture with Chinese herbs applying in 72 infant acute bronchitis cases and regarding to the humoral immune substances such as IgA, IgM, IgG, Complement C3 The result shows high cure and improve rate. The curative effect of infantile group is higher than that of childhood one (x2 = 6.501, 0.05 > p > 0.025). All indexes of humoral immune substances, especially IgA, were increased after treatment (t = 10.50, p < 0.01).

Acupuncture Points↗
PubMed1992

[A clinical analysis of atrial-ventricular sequential pacing].

Forty one patients were implanted DDD pacemakers (3 cases DDDR) from August, 1983 to July, 1990. 32 males and 9 females. The mean age was 62.3 years (range 32 to 91). 19 patients had coronary artery disease. The indication for pacing was II degrees-III degrees AV block in 16 patients and sick sinus syndrome in 25 patients. During follow-up period there were 2 patients had displacement, 4 patients had undersensing, 3 patients had pacemaker-mediated tachycardia and 3 patients had crosstalk. That was corrected through external programmer. The experience of this operation was discussed.

Adult↗
PubMed1992

Phases of dental fear for four treatment procedures among military personnel.

Dental fear is a significant problem in the delivery of dental care. This study examined the phases of dental fear in 488 military conscripts scheduled to receive four categories of dental treatment for the first time. Results showed that the level of fear increased gradually from the day before treatment and peaked while receiving it. A significant reduction occurred after completing the treatment. Among the different types of procedures, tooth extraction elicited the highest degree of fear, while having the teeth cleaned registered the lowest. Military servicemen showed a pattern of dental fear similar to those other population groups.

Adult↗
PubMed1991

A comparison of Ho's, International Union Against Cancer, and American Joint Committee stage classifications for nasopharyngeal carcinoma.

Five hundred sixty-four nasopharyngeal carcinomas (NPC), mostly of undifferentiated histologic type, were studied for survival, distant metastasis, and local recurrence. All had computerized tomography of the nasopharynx and skull base (CT-NP) and fiberoptic nasopharyngoscopy for evaluation of the primary tumor. Regional disease was assessed by palpation. A computer data base was formed on presentation, containing all information required for staging according to Ho's, the International Union Against Cancer (UICC), and the American Joint Committee (AJC) classifications. The three were compared for their efficacy in predicting prognosis. Ho's classification was superior to the other two because its overall stages differed from one another more significantly in the actuarial survival (ASR), disease-free survival (DFS), and freedom from distant metastasis (FDM) rates, and its N staging was more accurate in predicting FDM. Stages T1 and T2 of UICC/AJC were similar in the freedom from local recurrence rate (FLR) and should be grouped together, equivalent to Ho's T1. A more even patients number distribution among the stages also favored the use of Ho's classification.

Carcinoma↗
PubMed1991

A proposed modification of the Ho stage-classification for nasopharyngeal carcinoma.

Based on the clinical data of a retrospective study of 659 NPC patients with routine computed tomography of the nasopharyngeal region, a refinement of Ho's stage-classification for NPC is proposed with reduction in the number of overall stages without sacrificing the accuracy in predicting prognosis in the short term. Classifying the cervical lymph nodal metastasis into supraclavicular (Ho's N3) and above supraclavicular (Ho's N1 + N2) and the nasopharyngeal primary into early (Ho's T1 + T2n + T20) and advanced (Ho's T2p + T3 + T3p) forms the conceptual backbone of the present proposed modification of the original Ho stage-classification. Power in predicting the occurrence of distant metastases and the local failures has been enhanced by the proposed T-stage and N-stage re-grouping. Retrospective comparison between Ho's and the UICC stage-classifications showed a more even patients number distribution among the overall stages and a greater power in predicting NPC prognosis for the former. Prospective studies to compare the value of the different stage-classifications are required for recommendation of a single classification for general acceptance to facilitate comparison of treatment results between centres.

Dose-Response Relationship, Radiation↗
PubMed1991

The effect of the partition locus on plasmid stability and expression of a prolonged chemostat culture.

The stability, copy number, and gene expression of the pBR322 plasmid containing the par-locus under prolonged cultivation were studied. In the initial stage of the experiment it was observed that the par-locus had a stabilization effect on plasmid maintenance. This observation was consistent with previously reported results. However, after approximately 225 h, a mixed population of plasmid-containing and plasmid-free cells appeared. The mixed culture was stably maintained for approximately 200 h. In addition, the relative plasmid copy number showed an increase as compared to the par- culture. After 100 h the copy number decreased, reached a minimum, then stabilized. The beta-lactamase activity, was not significantly affected by the par-locus.

Base Sequence↗
PubMed1991

A retrospective comparison between different stage classifications for nasopharyngeal carcinoma.

From 1984 to 1987, 659 patients with untreated nasopharyngeal carcinoma (NPC) were investigated by computed tomography of the nasopharynx and skull base, and fibreoptic nasopharyngoscopy. Thirty-one patients presenting with distant metastasis were treated palliatively; 628 were treated with intent to cure. Prospective staging was performed for the Ho's classification but since all T- and N-stage data required for staging according to the Huang's, the Changsha and the UICC classifications were recorded and stored in a computer database, retrospective staging according to these classifications could be accurately performed. Ho's classification was concluded to be the best in view of highly significant differences between the overall stages in survival and between N-stages in distant metastasis. The number of prognostically distinct overall stages and N-stages was greatest for Ho's classification. Huang's T-stage classification was superior, however, because it emphasized the significant adverse effect on local tumour control of cranial nerve(s) palsy (Tn) and intracranial tumour extension (Tc). Changsha and UICC classifications were demonstrably less powerful in predicting NPC prognosis. Multiple sites of involvement within the nasopharynx by NPC had no adverse influence on local tumour control. The grouping together of both soft-tissue and skull-base lesions into Changsha's T3 has been shown to be unjustified because of significant differences in local failure.

Humans↗
PubMed1991

Treatment of essential hypertension with auriculoacupressure.

Auriculoacupressure was used in the treatment of 291 cases of essential hypertension, in comparison with 51 similar cases treated with Fufang Jiangya (composite hypotensive) Tablets. Analysis of results showed that the therapeutic effects in the 2 groups were similar, while the rate of marked efficacy in the acupressure group was higher than that of the medication group, and the level of blood lipids also significantly dropped (P less than 0.01); there was only minor improvement in blood rheology. In addition, acupressure manifested biphasic regulatory effects on sinus arrythmia. The curative effect of acupressure on essential vascular hypertension was good.

Acupuncture Points↗
PubMed1991

[Studies on the strain differences of Schistosoma japonicum in the mainland of China. III. Morphometric data].

The present investigation was undertaken to determine whether differences exist in the size of cercariae, adult worms and eggs among different isolates of S. japonicum in the mainland of China. Measurements on the corresponding stages of Japanese and Philippine strains of S. japonicum were also carried out for comparison. The size of cercariae collected from pooled naturally infected snails from different isolates was shown in Table 1. The body index of Yunnan isolate, which is defined as cercaria length x width (mm) x 1,000, was found to be smaller than those of the other 4 isolates, this difference being significant at p less than 0.01. Measurements of adult worms and eggs from different isolates were taken from various hosts infected with the same number of cercariae and for the same duration of infection. Results indicated that the mean length of mature worms and the size of mature eggs varied not only in different host species but also among host individuals of the same species infected with the same isolate of parasite. The mean length of mature worms of S. japonicum from various hosts infected with Yunnan isolate was considerably smaller than those of the other 4 isolates (Table 2), this difference being significant at p less than 0.05 by analysis of variance. Regarding the size (length x width) of eggs in mice and hamsters, large size eggs were found from both Yunnan and Guangxi isolates, while in rabbits and rhesus monkeys, large size eggs were found from Sichuan parasites.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗